Shower Stall Smells Like Rotten Eggs

If there is a rotten egg smell comming from you shower stall and you can't figure out where the smell is comming from.
You've used all kinds of cleaners, bleach and everything else you've tried.
There is usually a simple cure, tell who ever is peeing in the shower, while they are showering, to stop going pee and the smell usually goes away in a couple of days.
So snaking out the shower and all the cleaners in the world, will not help.
The only other thing it could be "but rare" and only in a tile shower stall and it was installed before the 80's when lead was still used.
If the lead pan below the tile leaked and the wood gets wet and rotten, sometimes it will cause the really bad smell.